1. Field of the Invention
The present invention relates to an improved drip chamber for use with intravenous fluid administration sets, and more particularly, to a drip chamber that includes an impinging member positioned in the flow path of the fluid such that the fluid strikes the impinging member and accumulates into droplets that are visible to medical personnel through the sidewalls of the drip chamber.
2. General Background
The use of drip chambers by medical personnel to regulate the flow of intravenous fluids to a patient are well known in the art. Generally, the drip chambers of such prior art devices are transparent to allow medical personnel to observe the flow rate or "drip" of the fluid and regulate the rate of delivery of the fluid to the patient. Illustrative prior art devices are described in U.S. Pat. No. 5,776,109, issued Jul. 7, 1998, to Hector Urrutia for a "Drip Chamber for Intravenous Fluid Delivery System", U.S. Pat. No. 4,601,712, issued Nov. 16, 1983, to James E. Cole et al., for a "Drip Chamber" and U.S. Pat. No. 4,395,260, issued Jun. 1, 1981, to Robert J. Todd et al. for a "Drip Chamber". One of the stated objects of these prior art devices is to introduce apparatus into the drip chamber to prevent the introduction of air bubbles in the pool of fluid contained at the bottom of the drip chamber when the flow rate of the fluid increases and forms a high velocity stream.
By introducing various types of apparatus into the drip chamber, these prior art devices appear to address the problem of air bubbles being introduced into the fluid. However, these devices require the introduction of features into the drip chamber that complicate the design of the drip chamber and may significantly increase manufacturing costs. More importantly, these devices fail to address the problem of the flow rate or "drip" of the fluid no longer being readily visible to medical personnel once the fluid forms a high velocity stream. The difficulty in discerning the high velocity fluid stream is particularly problematic with the use of "mini-drip" intravenous fluid administration sets (i.e. 60 drops/cc). In many lighting conditions, a fluid stream in such sets having a diameter of less than 1 mm will typically be virtually invisible to medical personnel.
The prior art devices that prevent the formation of air bubbles in the fluid pool by diverting the fluid stream against the sidewall of the drip chamber result in the fluid stream flowing down the sidewall and forming a "sheet" of fluid. Although this fluid stream is of a reduced velocity and may no longer form air bubbles in the fluid pool, the fluid stream may still be invisible to medical personnel. Thus, the flow rate of the fluid cannot be easily calculated by the medical personnel.
This same result may occur if the apparatus designed to impinge the fluid stream is connected to the sidewalls of the drip chamber. If the drip chamber is tilted or deformed for any reason such that the fluid strikes the apparatus at an angle, the fluid will flow across the apparatus to the sidewall and then down the sidewall forming an invisible "sheet" of fluid.
Thus, in view of the prior art, there is a need in the industry for a drip chamber for use with intravenous administration sets that includes an apparatus of a simple design positioned within the drip chamber such that the fluid strikes the apparatus and accumulates into droplets that are visible through the sidewalls of the drip chamber by medical personnel.